In recent years, the development of so-called "personal computers", or PCs for short, has enabled computing power to be made available to millions of people. In parallel with the development of the hardware, there has been major growth in the amount of software being written. In a PC system, the user operates the PC by first controlling it with the aid of software to be ready to operate in accordance with a desired programme, and then inputting data and producing output data from the PC.
In order to input data, a variety of devices may be used, the most common of which is a keyboard. The most common output device is a visual display unit (VDU) or screen on which the results of operations within the computer may be displayed to be read (if expressed in words) and/or viewed by the user.
Other input may be fed into the computer in known fashion. For example, most PCs have one or more communications ports which can send or receive data in the form of digital signals. The data can be received, e.g. from sensor units via appropriate interface circuits, or from other PCs. It is known that a very wide variety of sensors may be used, including sensors which sense human physiological parameters, for example blood pressure or electrical currents in the body (in computer-controlled electrocardiogram or electroencephalogram systems). However, up till now, such uses have been mainly confined to those where the computer user has not been the same person as the person under test.
An example where such use is not confined to those where the computer user has not been the same person is shown in published International Application WO 86/01317 which discloses using galvanic skin resistance to input data into a computer, and deals specifically with the electronics necessary to overcome the problem of the very wide range of galvanic skin resistances that may be sensed over a period of time and from one user to another.
Published International Application WO89/02247 discloses a system whereby a PC owner may monitor his or her heart activity using a simple probe which connects to the input of the computer. A suitable programme must be loaded into the computer in order to enable display or printout representative of the user's cardiac function to be effected. Published European Patent Application 0176220 also discloses using a computer to monitor a user's heart.
Published International Application WO 91/01699 discloses use of a computer and suitable sensor means to offer limited mobility and limb movement patients are means of operating a computer. United States Patent Specification 4894777 uses sensor means to detect when a computer user ceases to concentrate on the subject they should be concentrating on, and published UK Patent Specification 2079992A discloses using a sensor means and microcomputer to predict the fertility period in a woman's menstrual cycle.